DOC AIRBUS | AMM A320FAVIONICS EQUIPMENT VENTILATION - DESCRIPTION AND OPERATION
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1. General
Avionics Equipment Ventilation - General Arrangement ** ON A/C NOT FOR ALL
Avionics Equipment Ventilation - General Arrangement ** ON A/C NOT FOR ALL
Avionics Equipment Ventilation - General Arrangement ** ON A/C NOT FOR ALL
Avionics Equipment Ventilation - General Arrangement ** ON A/C NOT FOR ALL
The avionics ventilation system operates in different configurations. These configurations are dependent on, ambient temperature, whether the aircraft is on the ground, or in flight. The avionics equipment is also cooled in different ways, these are not dependent on the ventilation system configurations.
** ON A/C NOT FOR ALL Avionics Equipment Ventilation - General Arrangement ** ON A/C NOT FOR ALL Avionics Equipment Ventilation - General Arrangement ** ON A/C NOT FOR ALL Avionics Equipment Ventilation - General Arrangement ** ON A/C NOT FOR ALL Avionics Equipment Ventilation - General Arrangement ** ON A/C NOT FOR ALL 2. Component Location
Avionics Equipment Ventilation - Component Location ** ON A/C NOT FOR ALL
Avionics Equipment Ventilation - Component Location ** ON A/C NOT FOR ALL
Avionics Equipment Ventilation - Component Location ** ON A/C NOT FOR ALL
Avionics Equipment Ventilation - Component Location ** ON A/C NOT FOR ALL
Avionics Equipment Ventilation - Component Location ** ON A/C NOT FOR ALL
Avionics Equipment Ventilation - Component Location ** ON A/C NOT FOR ALL
Avionics Equipment Ventilation - Component Location ** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL Avionics Equipment Ventilation - Component Location ** ON A/C NOT FOR ALL Avionics Equipment Ventilation - Component Location ** ON A/C NOT FOR ALL Avionics Equipment Ventilation - Component Location ** ON A/C NOT FOR ALL Avionics Equipment Ventilation - Component Location ** ON A/C NOT FOR ALL Avionics Equipment Ventilation - Component Location ** ON A/C NOT FOR ALL Avionics Equipment Ventilation - Component Location ** ON A/C NOT FOR ALL Avionics Equipment Ventilation - Component Location ** ON A/C NOT FOR ALL | FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
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| 2140HM | CHECK VALVE-AVNCS VENT | 127 | 21-26-41 | ||
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| 10HQ | AEVC | 88VU | 128 | 21-26-34 | |
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| 10HQ | AEVC | 87VU | 128 | 21-26-34 | |
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| 10HQ | AEVC | 88VU | 128 | 21-26-34 | |
| ** ON A/C ALL | |||||
| 15HQ | VALVE-SKIN AIR INLET, AVNCS VENT | 127 | 21-26-52 | ||
| 16HQ | VALVE-SKIN EXCHANGER INLET BYPASS, AVNCS VENT | 128EG | 128 | 21-26-55 | |
| 17HQ | PRESS SW-BLOWER FAN, AVNCS VENT | 125 | 21-26-11 | ||
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| 18HQ | FAN-EXTRACT, AVNCS VENT | 824AR | 128 | 21-26-51 | |
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| 18HQ | FAN-EXTRACT, AVNCS VENT | 128 | 21-26-51 | ||
| ** ON A/C ALL | |||||
| 19HQ | PRESS SW-BLOWER FAN, AVNCS VENT | 127 | 21-26-11 | ||
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| 20HQ | FAN-BLOWER, AVNCS VENT | 824AR | 128 | 21-26-51 | |
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| 20HQ | FAN-BLOWER, AVNCS VENT | 128 | 21-26-51 | ||
| ** ON A/C ALL | |||||
| 21HQ | VALVE-COND AIR INLET, AVNCS VENT | 127 | 21-26-54 | ||
| 22HQ | VALVE-SKIN AIR OUTLET, AVNCS VENT | 126 | 21-26-53 | ||
| 23HQ | VALVE-SKIN EXCHANGER OUTLET BYPASS, AVNCS VENT | 125 | 21-26-55 | ||
| 24HQ | VALVE-SKIN EXCHANGER ISOL, AVNCS VENT | 128 | 21-26-55 | ||
| 25HQ | CAUT LT-ADIRU & AVNCS VENT | 108VU | 120 | 21-26-00 | |
| 26HQ | SENSOR-DUCT TEMP, AVNCS VENT | 824AR | 128 | 21-26-12 | |
| 28HQ | SENSOR-SKIN TEMP, AVNCS VENT | 126 | 21-26-13 | ||
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| 30HQ | PRESS SW-EXTRACT FAN, AVNCS VENT | 824AR | 128 | 21-26-11 | |
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| 30HQ | PRESS SW-EXTRACT FAN, AVNCS VENT | 128 | 21-26-11 | ||
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| 1WA | DET-SMOKE, AVNCS COMPT | 824AR | 128 | 26-15-15 | |
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| 1WA | DET-SMOKE, AVNCS COMPT | 128 | 26-15-15 | ||
| ** ON A/C ALL | |||||
| 2082HM | CARTRIDGE-AVNCS VENT FILTER | 127 | 21-26-43 | ||
| 2083HM | HOUSING-AVNCS VENT FILTER | 127 | 21-26-43 | ||
| 2095HM | SIPHON-AVNCS VENT FILTER | 127 | 21-20-00 | ||
| ** ON A/C NOT FOR ALL | |||||
| 2081HM | DEMISTER-AVNCS VENT FILTER | 127 | 21-26-43 | ||
| ** ON A/C ALL | |||||
| 2150HM | CHECK VALVE-AIR INLET, AVNCS VENT | 127 | 21-26-56 | ||
| ** ON A/C NOT FOR ALL | |||||
| 34HQ | SENSOR-DUCT TEMP, AVNCS VENT COMFORT | 128 | 21-26-12 | ||
3. System Description
The avionics equipment is cooled as listed below:
The avionics equipment is cooled as listed below:
A. Rack equipment
Equipment installed in the racks is cooled with air blown into the base of the racks through a sealed inlet (Ref. ARINC 600). This air then flows through the equipment to the top of the racks and is then removed through an unsealed outlet. Other equipment installed on the racks is cooled with air blown into the base and then out at the top.
Equipment installed in the racks is cooled with air blown into the base of the racks through a sealed inlet (Ref. ARINC 600). This air then flows through the equipment to the top of the racks and is then removed through an unsealed outlet. Other equipment installed on the racks is cooled with air blown into the base and then out at the top.
B. Cathode Ray Tubes (CRTs)
The CRTs located on the pilot's panel are cooled with air blown through a sealed inlet/outlet on the panel.
The CRTs located on the pilot's panel are cooled with air blown through a sealed inlet/outlet on the panel.
C. Pedestal Instruments
The pedestal instruments are cooled with air blown through the instruments on the upper panel and around the instruments on the lower panel. The air then goes into the avionics compartment through vents in the cockpit floor.
The pedestal instruments are cooled with air blown through the instruments on the upper panel and around the instruments on the lower panel. The air then goes into the avionics compartment through vents in the cockpit floor.
D. Cockpit Panels
The overhead circuit breaker and system control panels are cooled with cockpit air. This air is drawn around the back of the panels and into the avionics ventilation system.
The overhead circuit breaker and system control panels are cooled with cockpit air. This air is drawn around the back of the panels and into the avionics ventilation system.
E. Tranformer Rectifiers (TR)
The transformer rectifiers are cooled with avionics compartment air. This air is drawn through the equipment into the avionics ventilation system.
The transformer rectifiers are cooled with avionics compartment air. This air is drawn through the equipment into the avionics ventilation system.
F. Window Heat Controllers (WHC)
The WHCs are cooled with air blown through the equipment into the avionics compartment.
The WHCs are cooled with air blown through the equipment into the avionics compartment.
G. Radar
The radar is cooled by air blown into the equipment through a sealed inlet and blown out through an unsealed outlet (Ref. ARINC 600).
The radar is cooled by air blown into the equipment through a sealed inlet and blown out through an unsealed outlet (Ref. ARINC 600).
H. Batteries (Independent Circuit)
The batteries are cooled with avionics compartment air drawn through an inlet, around the batteries and overboard through a venturi. The ventilation is only effective with cabin differential pressure.
The batteries are cooled with avionics compartment air drawn through an inlet, around the batteries and overboard through a venturi. The ventilation is only effective with cabin differential pressure.
4. Power Supply
Described in the figures mentioned below.
** ON A/C NOT FOR ALL Described in the figures mentioned below.
5. Interfaces
Avionics Equipment Ventilation Schematic (Sheet 3/3) ** ON A/C NOT FOR ALL
Avionics Equipment Ventilation Schematic (Sheet 3/3) ** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL Avionics Equipment Ventilation Schematic (Sheet 3/3) ** ON A/C NOT FOR ALL Avionics Equipment Ventilation Schematic (Sheet 3/3) ** ON A/C NOT FOR ALL 6. Component Description
A. Avionics Equipment Ventilation Computer (AEVC) FIN: 10-HQ
Avionics Equipment Ventilation Computer (AEVC) - Location ** ON A/C NOT FOR ALL
Avionics Equipment Ventilation Computer (AEVC) - Location ** ON A/C NOT FOR ALL
The AEVC 10HQ is a 2MCU (Ref. ARINC 600) electronic assembly mounted on a chassis encased in a metal cover. The AEVC is located on shelf 87VU in the aft electronics rack 80VU. The AEVC controls the valves and fans in the avionics ventilation system.
Pressure switches and temperature sensors in the system send information related to the system status to the AEVC. The Engine Interface Unit (EIU) and the Landing Gear Control and Interface Unit (LGCIU) send additional information to the AEVC. The AEVC does a power-up test when electrical power is supplied and continuously monitors the system components.
The AEVC 10HQ is a 2MCU (Ref. ARINC 600) electronic assembly mounted on a chassis encased in a metal cover. The AEVC is located on shelf 86VU in the aft electronics rack 80VU. The AEVC controls the valves and fans in the avionics ventilation system.
Pressure switches and temperature sensors in the system send information related to the system status to the AEVC. The Engine Interface Unit (EIU) and the Landing Gear Control and Interface Unit (LGCIU) send additional information to the AEVC. The AEVC does a power-up test when electrical power is supplied and continuously monitors the system components.
Avionics Equipment Ventilation Computer (AEVC) - Location ** ON A/C NOT FOR ALL Avionics Equipment Ventilation Computer (AEVC) - Location ** ON A/C NOT FOR ALL Pressure switches and temperature sensors in the system send information related to the system status to the AEVC. The Engine Interface Unit (EIU) and the Landing Gear Control and Interface Unit (LGCIU) send additional information to the AEVC. The AEVC does a power-up test when electrical power is supplied and continuously monitors the system components.
The AEVC 10HQ is a 2MCU (Ref. ARINC 600) electronic assembly mounted on a chassis encased in a metal cover. The AEVC is located on shelf 86VU in the aft electronics rack 80VU. The AEVC controls the valves and fans in the avionics ventilation system.
Pressure switches and temperature sensors in the system send information related to the system status to the AEVC. The Engine Interface Unit (EIU) and the Landing Gear Control and Interface Unit (LGCIU) send additional information to the AEVC. The AEVC does a power-up test when electrical power is supplied and continuously monitors the system components.
B. Blower Fan
The blower fan 20HQ is powered with a three phase, four-pole single induction motor. The motor operates a fan-wheel which has high efficiency blades. It operates continuously at about 11,600 rpm. A thermo switch and relay are installed on the stator of the blower fan. If the temperature of the stator is 150 -5 DEG.C or +5 DEG.C (302 -9 DEG.F or +9 DEG.F), the thermo switch isolates the electrical supply to the fan. A fault indication light and reset button are installed on the fan body. The blower fan is safetied with the clamps to the brackets on the aircraft structure in the avionics compartment. Arrows on the fan casing show the direction of airflow through the fan and direction of the impeller rotation. If the impeller breaks up, the casing is strong enough to contain debris.
The blower fan 20HQ is powered with a three phase, four-pole single induction motor. The motor operates a fan-wheel which has high efficiency blades. It operates continuously at about 11,600 rpm. A thermo switch and relay are installed on the stator of the blower fan. If the temperature of the stator is 150 -5 DEG.C or +5 DEG.C (302 -9 DEG.F or +9 DEG.F), the thermo switch isolates the electrical supply to the fan. A fault indication light and reset button are installed on the fan body. The blower fan is safetied with the clamps to the brackets on the aircraft structure in the avionics compartment. Arrows on the fan casing show the direction of airflow through the fan and direction of the impeller rotation. If the impeller breaks up, the casing is strong enough to contain debris.
D. Skin Air Inlet Valve
The skin air inlet valve 15HQ is installed in the fuselage skin at the forward-lower left-hand side. This valve is an electrically-operated single-flap valve which can be manually overriden. When the aircraft is on the ground the valve is fully open. In flight, the valve is fully closed. On ground, if, after the take off sequence signal, the valve does not close, the ground crew can manually close it. Before the valve is closed manually, it first must be electrically isolated with a toggle switch located inside the valve.
The skin air inlet valve 15HQ is installed in the fuselage skin at the forward-lower left-hand side. This valve is an electrically-operated single-flap valve which can be manually overriden. When the aircraft is on the ground the valve is fully open. In flight, the valve is fully closed. On ground, if, after the take off sequence signal, the valve does not close, the ground crew can manually close it. Before the valve is closed manually, it first must be electrically isolated with a toggle switch located inside the valve.
E. Skin Air Outlet Valve
The skin air-outlet valve 22HQ is installed in the fuselage skin on the forward-lower right side. This valve is an electrically-operated single-flap valve that includes a second smaller flap. When the aircraft is on the ground, the valve is fully open. In flight, the valve is fully closed.
The smaller flap opens during the flight:
The skin air-outlet valve 22HQ is installed in the fuselage skin on the forward-lower right side. This valve is an electrically-operated single-flap valve that includes a second smaller flap. When the aircraft is on the ground, the valve is fully open. In flight, the valve is fully closed.
The smaller flap opens during the flight:
- When the skin temperature is more than 34 deg.C (93.20 deg.F) (partially open circuit)
- If there is smoke in the avionics ventilation system
- If the Avionics Equipment Ventilation Computer (AEVC) 10HQ does not operate correctly
- If the skin temperature sensor is incorrectly calibrated or does not operate.
F. Skin Exchanger Inlet Bypass Valve
Skin Exchanger Inlet Bypass Valve/Skin Exchanger Isolation Valve/ Skin Exchanger Outlet Bypass Valve
The skin exchanger inlet bypass valve 16HQ is installed downstream of the extract fan 18HQ in the tapping to the FWD underfloor area. This valve is of the butterfly type, with an actuator which moves the butterfly to the open or closed position. Two microswitches signal the valve position to the AEVC 10HQ. A visual position indicator is located on the top of the actuator unit.
The function of the valve is to discharge the excess ventilation air to the underfloor area.
Skin Exchanger Inlet Bypass Valve/Skin Exchanger Isolation Valve/ Skin Exchanger Outlet Bypass Valve The function of the valve is to discharge the excess ventilation air to the underfloor area.
G. Skin Exchanger Isolation Valve
Skin Exchanger Inlet Bypass Valve/Skin Exchanger Isolation Valve/ Skin Exchanger Outlet Bypass Valve
The skin exchanger isolation valve 24HQ is installed upstream of the skin heat exchanger. This valve is identical to the skin exchanger inlet bypass valve 16HQ.
Skin Exchanger Inlet Bypass Valve/Skin Exchanger Isolation Valve/ Skin Exchanger Outlet Bypass Valve H. Skin Exchanger Outlet Bypass Valve
Skin Exchanger Inlet Bypass Valve/Skin Exchanger Isolation Valve/ Skin Exchanger Outlet Bypass Valve
The skin exchanger outlet bypass valve 23HQ is installed downstream of the skin heat exchanger. This valve is identical to the skin exchanger inlet bypass valve 16HQ.
The function is to admit avionics compartment air into the system when the skin heat exchanger efficiency is degraded.
Skin Exchanger Inlet Bypass Valve/Skin Exchanger Isolation Valve/ Skin Exchanger Outlet Bypass Valve The function is to admit avionics compartment air into the system when the skin heat exchanger efficiency is degraded.
I. Conditioned Air Inlet Valve
The conditioned air inlet valve 21HQ is installed in a duct which is connected to the cockpit main supply duct. This valve is similar to the skin exchanger inlet bypass valve 16HQ.
The function is to admit cockpit supply air into the system to ensure the cooling function in case of failure.
The conditioned air inlet valve 21HQ is installed in a duct which is connected to the cockpit main supply duct. This valve is similar to the skin exchanger inlet bypass valve 16HQ.
The function is to admit cockpit supply air into the system to ensure the cooling function in case of failure.
J. Check Valve
The check valve 2140HM is installed downstream of the blower fan 20HQ. The check valve is installed in line between the ducts. Two semi- circular flaps are installed on a hinge-bar, a spring holds these semi-circular flaps in the closed position. Airflow from the blower fan 20HQ lifts the semi-circular flaps from their seats. This allows air to flow through the check valve to the avionics ventilation system. Airflow in the opposite direction through the check valve pushes the semi-circular flaps back onto their seats to stop the airflow. An arrow on the check valve casing shows the direction of the airflow through the check valve.
The check valve 2140HM is installed downstream of the blower fan 20HQ. The check valve is installed in line between the ducts. Two semi- circular flaps are installed on a hinge-bar, a spring holds these semi-circular flaps in the closed position. Airflow from the blower fan 20HQ lifts the semi-circular flaps from their seats. This allows air to flow through the check valve to the avionics ventilation system. Airflow in the opposite direction through the check valve pushes the semi-circular flaps back onto their seats to stop the airflow. An arrow on the check valve casing shows the direction of the airflow through the check valve.
K. Check Valve
The check valve 2150HM is installed aft of the skin air inlet valve 15HQ. The purpose of the check valve is to protect the system at the air inlet against possible adverse effect caused by cabin differential pressure.
The check valve 2150HM is installed aft of the skin air inlet valve 15HQ. The purpose of the check valve is to protect the system at the air inlet against possible adverse effect caused by cabin differential pressure.
L. Filter Assembly
The two-stage filter assembly 2081HM, 2082HM, 2083HM, 2095HM is installed upstream of the blower fan 20HQ. The first stage is a demister filter 2081HM which removes dust particles above 1000 microns and water particles. The second stage is a corrugated-cartridge-barrier filter 2082HM which removes any dust particles above 75 microns (Ref. ARINC 600).
The filter housing 2083HM is fitted with pressure test ports to check for clogging of both the demister filter and the dust filter cartridge. This can be achieved by means of a portable manometer.
The syphon assembly 2095HM is attached to the filter housing. Its function is to drain the water, filtered by the demister filter.
The two-stage filter assembly 2082HM, 2083HM is installed upstream of the blower fan 20HQ.
The filter features a centrifugal machine which removes water particules and a 5 micron disposable filter which removes any particule.
The filter assembly is designed to allow easy access for cleaning.
The two-stage filter assembly 2081HM, 2082HM, 2083HM, 2095HM is installed upstream of the blower fan 20HQ. The first stage is a demister filter 2081HM which removes dust particles above 1000 microns and water particles. The second stage is a corrugated-cartridge-barrier filter 2082HM which removes any dust particles above 75 microns (Ref. ARINC 600).
The filter housing 2083HM is fitted with pressure test ports to check for clogging of both the demister filter and the dust filter cartridge. This can be achieved by means of a portable manometer.
The syphon assembly 2095HM is attached to the filter housing. Its function is to drain the water, filtered by the demister filter.
The two-stage filter assembly 2082HM, 2083HM is installed upstream of the blower fan 20HQ.
The filter features a centrifugal machine which removes water particules and a 5 micron disposable filter which removes any particule.
The filter assembly is designed to allow easy access for cleaning.
M. Duct Temperature Sensor
The duct temperature sensor 26HQ is installed upstream of the aft electronics rack 80VU. It consists of a thermistor mounted in a stainless-steel tube with an electrical connector at the top.
If an overheat condition is detected, the indications and actions are the same for the blowing low flow as described in Para. 7.A.(4)(b).
The set temperature values are:
The duct temperature sensor 26HQ is installed upstream of the aft electronics rack 80VU. It consists of a thermistor mounted in a stainless-steel tube with an electrical connector at the top.
If an overheat condition is detected, the indications and actions are the same for the blowing low flow as described in Para. 7.A.(4)(b).
The set temperature values are:
- increasing temperatures 62 deg.C (143.6 deg.F) +1 deg.C (+33.8 deg.F),
- decreasing temperatures 60 deg.C (140 deg.F) +1 deg.C (+33.8 deg.F).
N. Pressure Switch
Pressure Switches 17HQ/19HQ/30HQ ** ON A/C NOT FOR ALL
Pressure Switches 17HQ/19HQ/30HQ ** ON A/C NOT FOR ALL
Three pressure switches 17HQ, 19HQ and 30HQ are installed in the avionics ventilation system, two in the blowing system and one in the extraction system. The switches are of the capsule/microswitch type with an electrical connector at the top. A low flow indication is given at a differential pressure of 1.7 mbar plus 1.3 or minus 0.5 mbar.
Pressure Switches 17HQ/19HQ/30HQ ** ON A/C NOT FOR ALL Pressure Switches 17HQ/19HQ/30HQ ** ON A/C NOT FOR ALL O. Skin Heat Exchanger
A skin heat exchanger is located in the upper fuselage between frames 12 and 14 and is used to cool the avionics ventilation air in normal flight operations. A thermally insulated internal wall is bolted to these frames to form two rectangular ducts. This internal wall is easily removed for structural inspection. A drainage system is included to remove any condensation when the heat exchanger is in operation.
A skin heat exchanger is located in the upper fuselage between frames 12 and 14 and is used to cool the avionics ventilation air in normal flight operations. A thermally insulated internal wall is bolted to these frames to form two rectangular ducts. This internal wall is easily removed for structural inspection. A drainage system is included to remove any condensation when the heat exchanger is in operation.
P. Smoke Detector
The smoke detector 1WA is installed upstream of the extract fan 18HQ. It is of the duct optical type used in stand alone mode with an electrical connector for connection to the warning circuits and the AEVC 10HQ (Ref. AMM D/O 26-00-00-00).
The smoke detector 1WA is installed upstream of the extract fan 18HQ. It is of the duct optical type used in stand alone mode with an electrical connector for connection to the warning circuits and the AEVC 10HQ (Ref. AMM D/O 26-00-00-00).
Q. Skin Temperature Sensor
The skin temperature sensor 28HQ is installed on the inside of the fuselage skin. It consists of a sensor element through which an electrical current passes to measure the potential difference proportional to the temperature.
The set temperature values are as follows:
The skin temperature sensor 28HQ is installed on the inside of the fuselage skin. It consists of a sensor element through which an electrical current passes to measure the potential difference proportional to the temperature.
NOTE: On the ground, the closed or open indication of the skin air valves can become amber on the ECAM, when the temperature is near to the opening or closing threshold.
This is because of the precision of the temperature sensors.
The set temperature values are as follows: This is because of the precision of the temperature sensors.
- on ground, increasing values +12 deg.C (53.60 deg.F), decreasing values +9 deg.C (48.20 deg.F),
- after takeoff increasing values +35 deg.C (95.00 deg.F), decreasing values +32 deg.C (89.60 deg.F).
The set temperature values are as follows:
- On the ground, increasing values +12 deg.C (53.60 deg.F), decreasing values +9 deg.C (48.20 deg.F)
- After takeoff, increasing values +35 deg.C (95.00 deg.F), decreasing values +32 deg.C (89.60 deg.F).
R. Comfort Duct Temperature-Sensor
The comfort duct temperature-sensor 34HQ is installed downstream of the aft electronics rack 80VU. It has a thermistor installed a stainless-steel tube with an electrical connector at the top.
It supplies the Avionics Equipment Ventilation Computer (AEVC) with the avionic extraction temperature-signal.
The set value for an increasing temperature is 40 deg.C (104 deg.F).
The comfort duct temperature-sensor 34HQ is installed downstream of the aft electronics rack 80VU. It has a thermistor installed a stainless-steel tube with an electrical connector at the top.
It supplies the Avionics Equipment Ventilation Computer (AEVC) with the avionic extraction temperature-signal.
The set value for an increasing temperature is 40 deg.C (104 deg.F).
7. Operation/Control and Indicating
A. Operation
Avionics Equipment Ventilation - Operation Table ** ON A/C NOT FOR ALL
Avionics Equipment Ventilation - Operation Table ** ON A/C NOT FOR ALL
Avionics Equipment Ventilation Schematic (Sheet 3/3) ** ON A/C NOT FOR ALL
Avionics Equipment Ventilation Schematic (Sheet 3/3) ** ON A/C NOT FOR ALL
The avionics equipment is cooled with air supplied in different ways depending on temperature conditions:
Avionics Equipment Ventilation - Operation Table ** ON A/C NOT FOR ALL Avionics Equipment Ventilation - Operation Table ** ON A/C NOT FOR ALL Avionics Equipment Ventilation Schematic (Sheet 3/3) ** ON A/C NOT FOR ALL Avionics Equipment Ventilation Schematic (Sheet 3/3) ** ON A/C NOT FOR ALL - open circuit,
- closed circuit,
- partially open circuit,
- cockpit supply air (in failure cases).
(1) Open circuit
The avionics equipment is cooled with ambient air when the aircraft is on the ground and the skin temperature is above +12 deg.C (53.60 deg.F). Ambient air, drawn through the skin air inlet valve 15HQ is blown through the check valve 2150HM and filter assembly 2081HM, 2082HM, 2083HM. The air drawn by the blower fan 20HQ is blown through the check valve 2140HM into the system. The air, after cooling the equipment, is drawn by the extract fan 18HQ directly overboard through the skin air outlet valve 22HQ. The skin heat exchanger is by-passed because the skin exchanger isolation valve 24HQ is closed.
The avionics equipment is cooled with ambient air when the aircraft is on the ground and the skin temperature is above +12 deg.C (53.60 deg.F). Ambient air, drawn through the skin air inlet valve 15HQ is blown through the check valve 2150HM and filter assembly 2081HM, 2082HM, 2083HM. The air drawn by the blower fan 20HQ is blown through the check valve 2140HM into the system. The air, after cooling the equipment, is drawn by the extract fan 18HQ directly overboard through the skin air outlet valve 22HQ. The skin heat exchanger is by-passed because the skin exchanger isolation valve 24HQ is closed.
(2) Closed Circuit
Normally the avionics equipment is cooled with air in a closed circuit when:
When this signal is received by the AEVC 10HQ, a warning message shows:
The skin exchanger inlet bypass valve 16HQ opens when the pressure switches detect a correct pressure/airflow in the system.
Normally the avionics equipment is cooled with air in a closed circuit when:
- The aircraft is on the ground and the skin temperature is below +9 deg.C (48.20 deg.F),
- or when the aircraft is in flight and the skin temperature is below +32 deg.C (89.60 deg.F).
When this signal is received by the AEVC 10HQ, a warning message shows:
- "VENT BLOWER FAULT" when a decreasing pressure/airflow is detected by the pressure switches 17HQ and 19HQ
- "VENT EXTRACT FAULT" when a decreasing pressure/airflow is detected by pressure switch 30HQ.
- The OVRD Blower pushbutton or
- The OVRD Extract pushbutton or
- The OVRD Blower and OVRD Extract pushbuttons
The skin exchanger inlet bypass valve 16HQ opens when the pressure switches detect a correct pressure/airflow in the system.
(3) Closed circuit
In normal conditions, a closed air circuit is used for the cooling of the avionics equipment:
When the AEVC 10HQ receives this signal, a warning message comes into view:
The skin-exchanger inlet bypass-valve 16HQ opens again when the pressure switches sense a correct pressure/airflow in the system.
In normal conditions, a closed air circuit is used for the cooling of the avionics equipment:
- On the ground, when the skin temperature is less than +9 deg.C (48.20 deg.F)
- After landing, if the comfort duct temperature-sensor 34HQ senses a temperature of less than +40 deg.C (104.00 deg.F)
- In flight, when the skin temperature is less than +32 deg.C (89.60 deg.F).
When the AEVC 10HQ receives this signal, a warning message comes into view:
- VENT BLOWER FAULT, when the pressure switches 17HQ and 19HQ sense that the pressure/airflow decreases
- VENT EXTRACT FAULT, when the pressure switch 30HQ senses that the pressure/airflow decreases.
The skin-exchanger inlet bypass-valve 16HQ opens again when the pressure switches sense a correct pressure/airflow in the system.
(4) Partially Open Circuit
The avionics equipment is cooled with air in a partially open circuit when the skin temperature is above or equal to +35 deg.C (95.00 deg.F) and:
The air after cooling the equipment is directed overboard through the skin air outlet valve 22HQ and to the forward underfloor area through the skin exchanger inlet bypass valve 16HQ. When the skin temperature drops below +32 deg.C (89.60 deg.F), the system goes back to a closed circuit configuration.
The avionics equipment is cooled with air in a partially open circuit when the skin temperature is above or equal to +35 deg.C (95.00 deg.F) and:
- When the aircraft is on the ground (TLA above T/O),
- When the aircraft is in flight.
- The skin exchanger outlet bypass valve 23HQ to open,
- The skin air outlet valve 22HQ to partially open,
- The skin exchanger inlet bypass valve 16HQ to open.
The air after cooling the equipment is directed overboard through the skin air outlet valve 22HQ and to the forward underfloor area through the skin exchanger inlet bypass valve 16HQ. When the skin temperature drops below +32 deg.C (89.60 deg.F), the system goes back to a closed circuit configuration.
NOTE: If the skin temperature is below -50 deg.C (-58.00 deg.F) during more than 5 seconds and if the pushbuttons EXTRACT, BLOWER and DITCHING are pushed (normal operation), the system is in a partially open circuit configuration. A reset of the AEVC sets the system to a closed circuit configuration.
(5) Cockpit Supply Air
The avionics equipment is cooled with air tapped from the cockpit supply duct when one of the following failure cases occurs:
The avionics equipment is cooled with air tapped from the cockpit supply duct when one of the following failure cases occurs:
(a) Extraction Low Flow
The AEVC 10HQ illuminates the FAULT legend on the EXTRACT pushbutton switch 14HQ if the pressure switch 30HQ detects low flow. On the ground, the ADIRU & AVNCS VENT caution light 25HQ comes on amber on the external power panel 108VU and the horn sounds. When this happens, the pushbutton switch must be released and the OVRD legend comes on. This causes the conditioned air inlet valve 21HQ and skin exchanger isolation valve 24HQ to open. All the other valves close.
The AEVC 10HQ illuminates the FAULT legend on the EXTRACT pushbutton switch 14HQ if the pressure switch 30HQ detects low flow. On the ground, the ADIRU & AVNCS VENT caution light 25HQ comes on amber on the external power panel 108VU and the horn sounds. When this happens, the pushbutton switch must be released and the OVRD legend comes on. This causes the conditioned air inlet valve 21HQ and skin exchanger isolation valve 24HQ to open. All the other valves close.
(b) Blowing Low Flow/High Duct Temperature
The AEVC 10HQ illuminates the FAULT legend on the BLOWER pushbutton switch 13HQ when one or both of the following occurs:
When this happens, the pushbutton switch must be released and the OVRD legend comes on. This causes the blower fan 20HQ to stop, the conditioned air inlet valve 21HQ to open and the skin exchanger isolation valve 24HQ to open. All the other valves close.
The AEVC 10HQ illuminates the FAULT legend on the BLOWER pushbutton switch 13HQ when one or both of the following occurs:
- if the pressure switch 17HQ (19HQ) detects low flow,
- if the temperature sensor 26HQ senses high duct temperature.
When this happens, the pushbutton switch must be released and the OVRD legend comes on. This causes the blower fan 20HQ to stop, the conditioned air inlet valve 21HQ to open and the skin exchanger isolation valve 24HQ to open. All the other valves close.
(c) Smoke (Ref. AMM D/O 26-15-00-00)
If the smoke detector 1WA detects smoke, the AEVC 10HQ triggers illumination of:
If the smoke detector 1WA detects smoke, the AEVC 10HQ triggers illumination of:
- the SMOKE legend of the GEN 1 LINE pushbutton switch on the panel 21VU,
- the FAULT legends of the BLOWER and EXTRACT pusbutton switches on the panel 22VU.
When this happens, the BLOWER pushbutton switch 13HQ and the EXTRACT pushbutton switch 14HQ must be released. and the OVRD legends come on. This causes the blower fan 20HQ to stop, the conditioned air inlet valve 21HQ to open and the skin air outlet valve 22HQ to partially open. All the other valves close and the air is directed overboard through the skin air outlet valve 22HQ.
(d) AEVC Power Supply Cutoff
If the AEVC 10HQ stops operating, the FAULT legends on the EXTRACT pushbutton switch 14HQ and the BLOWER pushbutton switch 13HQ come on amber. When this happens, both pushbutton switches must be released and the OVRD legends come on. This causes the blower fan 20HQ to stop, the conditioned air inlet valve 21HQ to open and the skin air outlet valve 22HQ to partially open. All the other valves remain in their last controlled position.
If the AEVC 10HQ stops operating, the FAULT legends on the EXTRACT pushbutton switch 14HQ and the BLOWER pushbutton switch 13HQ come on amber. When this happens, both pushbutton switches must be released and the OVRD legends come on. This causes the blower fan 20HQ to stop, the conditioned air inlet valve 21HQ to open and the skin air outlet valve 22HQ to partially open. All the other valves remain in their last controlled position.
B. Control and Indicating
(1) EXTRACT Pushbutton Switch
AUTO - (pushbutton switch pressed): normal operation. In case of failure, the FAULT legend comes on amber.
OVRD - (pushbutton switch released): the FAULT legend goes off, the OVRD legend comes on white.
The conditioned air inlet valve 21HQ and skin exchanger isolation valve 24HQ open, all the other valves close.
AUTO - (pushbutton switch pressed): normal operation. In case of failure, the FAULT legend comes on amber.
OVRD - (pushbutton switch released): the FAULT legend goes off, the OVRD legend comes on white.
The conditioned air inlet valve 21HQ and skin exchanger isolation valve 24HQ open, all the other valves close.
(2) BLOWER Pushbutton Switch
AUTO - (pushbutton switch pressed): normal operation. In case of failure, the FAULT legend comes on amber.
OVRD - (pushbutton switch released): the FAULT legend goes off, the OVRD legend comes on white. The blower fan 20HQ stops, the conditioned air inlet valve 21HQ and the skin exchanger isolation valve 24HQ open. All the other valves close, and the extract fan 18HQ continues to operate.
If smoke is detected, both pushbutton switches are released. The conditioned air inlet valve 21HQ opens, the skin air outlet valve 22HQ partially opens. All the other valves close and the extract fan 18HQ continues to operate.
The horn sounds to alert the ground crew in the event of low flow or overheat when the avionics ventilation system is in operation.
AUTO - (pushbutton switch pressed): normal operation. In case of failure, the FAULT legend comes on amber.
OVRD - (pushbutton switch released): the FAULT legend goes off, the OVRD legend comes on white. The blower fan 20HQ stops, the conditioned air inlet valve 21HQ and the skin exchanger isolation valve 24HQ open. All the other valves close, and the extract fan 18HQ continues to operate.
If smoke is detected, both pushbutton switches are released. The conditioned air inlet valve 21HQ opens, the skin air outlet valve 22HQ partially opens. All the other valves close and the extract fan 18HQ continues to operate.
The horn sounds to alert the ground crew in the event of low flow or overheat when the avionics ventilation system is in operation.
NOTE: If the ventilation system is defective or when the BLOWER and EXTRACT pushbutton switches are released (OVRD legends on):
- there are no more colored backgrounds on the EFIS displays.
(3) EXTRACT Pushbutton Switch
AUTO - (pushbutton switch pressed): normal operation. In case of failure, the FAULT legend comes on amber.
OVRD - (pushbutton switch released): the FAULT legend goes off, the OVRD legend comes on white.
The conditioned-air inlet valve 21HQ and skin exchanger isolation-valve 24HQ open, all the other valves close.
AUTO - (pushbutton switch pressed): normal operation. In case of failure, the FAULT legend comes on amber.
OVRD - (pushbutton switch released): the FAULT legend goes off, the OVRD legend comes on white.
The conditioned-air inlet valve 21HQ and skin exchanger isolation-valve 24HQ open, all the other valves close.
(4) BLOWER Pushbutton Switch
AUTO - (pushbutton switch pressed): normal operation. In case of failure, the FAULT legend comes on amber.
OVRD - (pushbutton switch released): the FAULT legend goes off, the OVRD legend comes on white. The blower fan 20HQ stops, the conditioned-air inlet valve 21HQ and the skin exchanger isolation-valve 24HQ open. All the other valves close, and the extract fan 18HQ continues to operate.
If smoke is detected, both pushbutton switches are released. The conditioned-air inlet valve 21HQ opens, the skin air-outlet valve 22HQ partially opens. All the other valves close and the extract fan 18HQ continues to operate.
The horn operates if there is low flow or overheat when the avionics ventilation system is in operation.
AUTO - (pushbutton switch pressed): normal operation. In case of failure, the FAULT legend comes on amber.
OVRD - (pushbutton switch released): the FAULT legend goes off, the OVRD legend comes on white. The blower fan 20HQ stops, the conditioned-air inlet valve 21HQ and the skin exchanger isolation-valve 24HQ open. All the other valves close, and the extract fan 18HQ continues to operate.
If smoke is detected, both pushbutton switches are released. The conditioned-air inlet valve 21HQ opens, the skin air-outlet valve 22HQ partially opens. All the other valves close and the extract fan 18HQ continues to operate.
The horn operates if there is low flow or overheat when the avionics ventilation system is in operation.
8. BITE Test
TEST Procedure from the CFDS ** ON A/C NOT FOR ALL
TEST Procedure from the CFDS ** ON A/C NOT FOR ALL
LAST LEG REPORT from the CFDS ** ON A/C NOT FOR ALL
LAST LEG REPORT from the CFDS ** ON A/C NOT FOR ALL
CLASS 3 FAULTS from the CFDS ** ON A/C NOT FOR ALL
CLASS 3 FAULTS from the CFDS ** ON A/C NOT FOR ALL
The built-in-test function is fully done by the software program. It monitors the operation of the AEVC and ensures that the inputs are correct. The data which are known as incorrect are kept in the EEPROM.
The BITE can operate during aircraft energization and permanently. The CFDIU can also monitor the BITE.
TEST Procedure from the CFDS ** ON A/C NOT FOR ALL TEST Procedure from the CFDS ** ON A/C NOT FOR ALL LAST LEG REPORT from the CFDS ** ON A/C NOT FOR ALL LAST LEG REPORT from the CFDS ** ON A/C NOT FOR ALL CLASS 3 FAULTS from the CFDS ** ON A/C NOT FOR ALL CLASS 3 FAULTS from the CFDS ** ON A/C NOT FOR ALL The BITE can operate during aircraft energization and permanently. The CFDIU can also monitor the BITE.
A. AEVC power-up test
(1) Conditions of power-up test initialization
(a) Necessary computer de-energization time:
- 1 sec.
(b) A/C configuration:
- A/C on ground
- VENTILATION section of the panel 22VU:
BLOWER and EXTRACT pushbutton switches in AUTO configuration (pushed) - CABIN PRESS section of the panel 25VU:
DITCHING pushbutton switch released (the ON legend is off)
NOTE: When the BLOWER and EXTRACT pushbutton switches are released (the OVRD legends are on) and the DITCH pushbutton switch is pushed (the ON legend is on), the power-up test is inhibited.
(2) Progress of power-up test
(a) Duration:
- 85 sec.
(b) Cockpit repercussions (ECAM warning, audio warning,pushbutton flashing... if any...):
- VENTILATION section of the panel 22VU:
FAULT legend of the BLOWER and EXTRACT pushbutton switches comes on amber - EMER ELEC PWR section of the panel 21VU:
SMOKE legend of the GEN 1 LINE pushbutton switch comes on - ECAM PRESS page:
Skin valves move to fully open position
(3) Results of power-up test
(a) Test passed:
- No message
(b) Test failed:
- MASTER CAUT light on with single chime
- ECAM warning:
VENT AVNCS SYS FAULT - ECAM PRESS page:
Normal display